ISSN:
1432-0630
Schlagwort(e):
78.70.D
;
81.90.+c
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Maschinenbau
,
Physik
Notizen:
Abstract Both lifetime and angular correlation of positron annihilation have been measured for a series of synthetic zeolites for which the void structures are known fairly well. All of the zeolites had long lifetime components and a narrow momentum component which are ascribable to o-Ps and p-Ps annihilations in the voids, respectively. The correlation between the width of the p-Ps narrow component and the size of the largest voids showed a remarkable agreement with a theoretical estimate based on the spherical potential well model. The measurement of p-Ps momentum thus appears to be prospective as a tool to determine the size of voids of materials. The lifetime of the long lifetime component, on the other hand, showed a poor correlation with the void size even from a qualitative viewpoint, suggesting that factors other than the simple void size effect are dominant in determining the o-Ps lifetimes. Discussion is made on the cause of the different dependences of o-Ps and p-Ps annihilation parameters on the void size. It has also been found that p-Ps fraction is always larger than one third of the o-Ps fraction in all the zeolites studied. A discussion is presented on this point, too.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00615004
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